26-03-2012, 04:01 PM
Telecommunication
RS.docx (Size: 17.22 KB / Downloads: 34)
RS-232
In telecommunications, RS-232 (Recommended Standard 232) is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE (Data Terminal Equipment) and a DCE (Data Circuit-terminating Equipment). It is commonly used in computer serial ports. The standard defines the electrical characteristics and timing of signals, the meaning of signals, and the physical size and pin out of connectors. The current version of the standard is TIA-232-F Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange, issued in 1997.
An RS-232 port was once a standard feature of a personal computer for connections to modems, printers, mice, data storage, un-interruptible power supplies, and other peripheral devices. However, the limited transmission speed, relatively large voltage swing, and large standard connectors motivated development of the universal serial bus which has displaced RS-232 from most of its peripheral interface roles. Many modern personal computers have no RS-232 ports and must use an external converter to connect to older peripherals. Some RS-232 devices are still found especially in industrial machines or scientific instruments.
RS-449
The RS-449 specification, also known as EIA-449 or TIA-449, defines the functional and mechanical characteristics of the interface between data terminal equipment and data communications equipment.
The electrical signaling standards intended for use with RS-449 are RS-422 for balanced signals, and RS-423 for the unbalanced signals, with data rates to 2 Mbit/s. The standard specifies DC-37 and DE-9 for the primary and secondary data circuits. Though never applied on personal computers, this interface is found on some network communication equipment. The full title of the standard is EIA-449 General Purpose 37-Position and 9-Position Interface for Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange.
X.21
X.21 (sometimes referred to as X21) is an interface specification for differential communications introduced in the mid 1970s by the ITU-T. X.21 was first introduced as a means to provide a digital signaling interface for telecommunications between carriers and customers' equipment. This includes specifications for DTE/DCE physical interface elements, alignment of call control characters and error checking, elements of the call control phase for circuit switching services, and test loops.
When X.21 is used with V.11, it provides synchronous data transmission at rates from 600 bit/s to 10 Mbit/s. There is also a variant of X.21 that is only used in select legacy applications, “circuit switched X.21”. X.21 normally is found on a 15-pin D-Sub connector and is capable of running full-duplex data transmissions.
RS.docx (Size: 17.22 KB / Downloads: 34)
RS-232
In telecommunications, RS-232 (Recommended Standard 232) is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE (Data Terminal Equipment) and a DCE (Data Circuit-terminating Equipment). It is commonly used in computer serial ports. The standard defines the electrical characteristics and timing of signals, the meaning of signals, and the physical size and pin out of connectors. The current version of the standard is TIA-232-F Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange, issued in 1997.
An RS-232 port was once a standard feature of a personal computer for connections to modems, printers, mice, data storage, un-interruptible power supplies, and other peripheral devices. However, the limited transmission speed, relatively large voltage swing, and large standard connectors motivated development of the universal serial bus which has displaced RS-232 from most of its peripheral interface roles. Many modern personal computers have no RS-232 ports and must use an external converter to connect to older peripherals. Some RS-232 devices are still found especially in industrial machines or scientific instruments.
RS-449
The RS-449 specification, also known as EIA-449 or TIA-449, defines the functional and mechanical characteristics of the interface between data terminal equipment and data communications equipment.
The electrical signaling standards intended for use with RS-449 are RS-422 for balanced signals, and RS-423 for the unbalanced signals, with data rates to 2 Mbit/s. The standard specifies DC-37 and DE-9 for the primary and secondary data circuits. Though never applied on personal computers, this interface is found on some network communication equipment. The full title of the standard is EIA-449 General Purpose 37-Position and 9-Position Interface for Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange.
X.21
X.21 (sometimes referred to as X21) is an interface specification for differential communications introduced in the mid 1970s by the ITU-T. X.21 was first introduced as a means to provide a digital signaling interface for telecommunications between carriers and customers' equipment. This includes specifications for DTE/DCE physical interface elements, alignment of call control characters and error checking, elements of the call control phase for circuit switching services, and test loops.
When X.21 is used with V.11, it provides synchronous data transmission at rates from 600 bit/s to 10 Mbit/s. There is also a variant of X.21 that is only used in select legacy applications, “circuit switched X.21”. X.21 normally is found on a 15-pin D-Sub connector and is capable of running full-duplex data transmissions.